Neuroblastoma may have varied manifestations. One of the characteristics of a neuroblastoma is the vagueness of symptomatology than often leads to delay in diagnosis. Less than half present the children may resent with a palpable abdominal mass. Herein the authors describe an unsual case of a right flank mass owing to congenital hydronephrosis with ureteropelvic junction obstruction and an ipsilateral adrenal neuroblastoma discovered at operation.